silent key
n.— «Was a licensed amateur (ham) radio with the call sign KA6HVA. When he passed away, he became, in ham radio parlance, a “silent key.”» —“Biography for Burl Ives” The Internet Movie Database Aug. 13, 2008. (source: Double-Tongued Dictionary)
Further reading
Among ham radio enthusiasts, the word Elmer has become an affectionate term for an experienced ham radio operator who mentors a novice. It’s also used as a verb: Elmering someone means helping a new ham. The term was coined in a 1971 magazine...
Debbie from Memphis, Tennessee, grew up in Arkansas, where she learned the term trade-last, which refers to “a quoted compliment offered in return for the recipient first offering one to the speaker.” Although those from the American South may...
The journal of the Radio Society of Great Britain (RSGB) used to have an obituary column headed “Silent Keys”. It probably still does, but I have not been a member since the late sixties.